Are polycarbonates amorphous or crystalline?

Question

We are using x-ray diffraction to search for ammonium sulfide on polycarbonate filters which we use to test the air. Unfortunately, when running a blank, we found a peak exactly where ammonium sulfide would have a peak. Can anyone offer any insight? Please give as detailed an answer as possible.

Answer 1

This obviously points to an impurity in the blank or a substance isomorphous with (NH4)2S. I suggest using an ultrapure blank. Polycarbonates may break down in their long range order thus getting amorphous.